Yoga clothing company lululemon athletica (Nasdaq: LULU) has sued Calvin Klein and G-III Apparel Group (Nasdaq: GIII), a Calvin Klein supplier, claiming that Calvin Klein, which is owned by PVH (NYSE: PVH), is carrying pants that violate three of its patents.

The Canadian company filed the suit in a federal court in Delaware last month. Reuters reported that the company singled out two Calvin Klein "Performance" brand pants that it believes are manufactured and supplied by G-III Apparel.

"When we see attempts to mirror our product we will take the necessary steps to protect our assets," The Globe and Mail quoted lululemon Chief Executive Officer Christine Day as saying last week.

The Wall Street Journal this week took a look at the case and what seems to be a novel approach in the apparel world.